The largest Bitcoin exchange has filed key paperwork with the US Treasury's anti-money laundering agency, but it may have come too late. Mt. Gox, based in Tokyo, registered on Thursday with the Financial Crimes Enforcement Network (FinCEN) as a money services business (MSB), according to FinCEN's website. The adoption of Bitcoin, a virtual currency that can be transferred worldwide for free using peer-to-peer software, has been stymied by concerns over compliance with different countries' anti-money laundering and financial regulations. Mt. Gox's registration comes just six weeks after one of its U.S. bank accounts was seized. The order alleged Mt. Gox failed to register as a money transmitting business, which is required by many states and the federal government. The account was linked to Dwolla, a payments provider, and used by Mt. Gox to transmit funds to its exchange i...